Light field display device and method of manufacturing the same

ABSTRACT

A light field display device according to example embodiments includes a lower substrate, a back plane structure on the lower substrate, a first electrode electrically connected to the back plane structure, an organic light emitting layer on the first electrode, a second electrode facing the first electrode and covering the organic light emitting layer, an encapsulation layer covering the second electrode, a lower alignment layer directly on the encapsulation layer, a liquid crystal layer on the lower alignment layer, the liquid crystal layer including a plurality of micro liquid crystal lenses to constitute a microlens array, a lens electrode on the liquid crystal layer to form an electric field with the second electrode, and an upper substrate on the lens electrode.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 15/685,859 filed on Aug. 24, 2017, which claims priority under35 USC § 119 to Korean Patent Application No. 10-2016-0142385, filed onOct. 28, 2016 in the Korean Intellectual Property Office (KIPO), thedisclosures of which are hereby incorporated by reference herein intheir entirety.

BACKGROUND 1. Field

Example embodiments of the inventive concept relate to display devices.More particularly, example embodiments of the inventive concept relateto light field display devices and methods of manufacturing the same.

2. Discussion of Related Art

The stereoscopic display technology is applied to a variety of imagedisplay fields such as movies, TVs, and mobile display devices. Theultimate goal of stereoscopic image display is to enable people toexperience the same three-dimensional effect as they would experience ina real environment. To do this, many kinds of techniques such as stereomethods and multi view methods have been studied. Among them, a lightfield method for the stereoscopic image can reproduce thethree-dimensional spatial information more accurately than the stereomethod or the multi view method.

Active liquid crystal lenses for implementing a lens by controlling adirection distribution of liquid crystal molecules with an electricfield have been recently researched. The liquid crystal lenses includean upper substrate, a lower substrate, and a thick liquid crystal layerbetween the upper and lower substrates. The liquid crystal lensesinclude a plurality of lens electrodes. Different voltages are appliedto the respective lens electrodes to control the direction distributionof liquid crystal molecules. A two dimensional (2D) image display modeand a stereoscopic image display mode may be switched by the liquidcrystal control.

However, typical 2D/3D switchable display devices simply include aliquid crystal display (LCD) panel and a liquid crystal lens panelattached to the LCD panel by using an optically clear adhesive (OCA) andthe liquid crystal lens panel includes the thick and rigid upper andlower substrates, the plurality of electrodes and the liquid crystallayer. Accordingly, it is difficult to reduce a thickness of the lightfield display device, use an organic light emitting display panel, andrealize a flexible light field display device.

SUMMARY

Example embodiments provide a light field display device in which analignment layer and/or a lens electrode are directly formed on anorganic light emitting display panel.

Example embodiments provide a method of manufacturing a light fielddisplay device for integrating an alignment layer and/or a lenselectrode on an organic light emitting display panel.

According to example embodiments, a light field display device maycomprise a lower substrate, a back plane structure on the lowersubstrate, a first electrode electrically connected to the back planestructure, an organic light emitting layer on the first electrode, asecond electrode facing the first electrode and covering the organiclight emitting layer, an encapsulation layer covering the secondelectrode, a lower alignment layer directly on the encapsulation layer,a liquid crystal layer on the lower alignment layer, the liquid crystallayer including a plurality of micro liquid crystal lenses to constitutea microlens array, a lens electrode on the liquid crystal layer to forman electric field with the second electrode, and an upper substrate onthe lens electrode.

In example embodiments, a voltage may be applied to the lens electrodein a stereoscopic image display mode to form the electric field betweenthe lens electrode and the second electrode.

In example embodiments, the light field display device may furthercomprise an upper alignment layer between the liquid crystal layer andthe lens electrode.

In example embodiments, the lens electrode may have a plurality ofannular patterns, and wherein each of the micro liquid crystal lenses issurrounded by an annular pattern of the plurality of annular patterns.

In example embodiments, a planar shape of each of the micro liquidcrystal lenses surrounded by the lens electrode may be circular orelliptical.

In example embodiments, the lens electrode may include a plurality ofcircular or elliptical openings corresponding to the micro liquidcrystal lenses.

In example embodiments, a planar shape of the lens electrode is aquadrilateral shape having a plurality of circular or ellipticalopenings corresponding to the micro liquid crystal lenses.

In example embodiments, the lens electrode has a plurality of hexagonalopenings and a planar shape of each of the micro liquid crystal lensessurrounded by the lens electrode may be substantially hexagonal.

In example embodiments, a width of each of the annular patterns may bewithin a range of about 3% to about 20% of a pitch of each of the microliquid crystal lenses.

In example embodiments, the light field display device may furthercomprise a touch sensing unit on the upper substrate.

According to example embodiments, a light field display device maycomprise an organic light emitting display panel including a lowersubstrate, an encapsulation layer, and a plurality of sub pixelsarranged in a matrix form between the lower substrate and theencapsulation layer, a lower lens electrode directly on theencapsulation layer, a lower alignment layer directly on theencapsulation layer, a liquid crystal layer on the lower alignmentlayer, the liquid crystal layer including a plurality of micro liquidcrystal lenses to constitute a microlens array, an upper alignment layeron the liquid crystal layer, an upper lens electrode on the liquidcrystal layer to form an electric field with the lower electrode lens byreceiving a voltage, and an upper substrate on the upper lens electrode.

In example embodiments, the lower lens electrode may be facing the subpixels in common and the upper lens electrode may have a plurality ofannular patterns, and wherein each of the micro liquid crystal lenses issurrounded by an annular pattern of the plurality of annular patterns.

In example embodiments, the upper lens electrode may be facing the subpixels in common and the lower lens electrode may have a plurality ofannular patterns, and wherein each of the micro liquid crystal lenses issurrounded by an annular pattern of the plurality of annular patterns.

In example embodiments, the lower lens electrode and the upper lenselectrode may have annular patterns alternating with each other in afirst direction in which the micro liquid crystal lenses are arranged. Apart of an edge of the lower lens electrode may overlap a part of anedge of the upper lens electrode.

According to example embodiments, a method of manufacturing a lightfield display device may comprise forming an organic light emittingdisplay panel in which a lower substrate, a back plane structure, afirst electrode, a organic light emitting layer, a second electrode, andan encapsulation layer covering the second electrode are sequentiallystacked, forming a lower alignment layer on the encapsulation layer,patterning an upper lens electrode on a lower surface of an uppersubstrate, the upper lens electrode forming an electric field with thesecond electrode, forming an upper alignment layer on the lower surfaceof the upper substrate to cover the upper lens electrode, forming aliquid crystal layer on the lower alignment layer or the upper alignmentlayer to constitute a microlens array having a plurality of micro liquidcrystal lenses, and attaching the upper substrate to the encapsulationlayer so that the liquid crystal layer is between the lower alignmentlayer and the upper alignment.

In example embodiments, forming the lower alignment layer may includedirectly coating a polyimide-based polymer resin on an upper surface ofthe encapsulation layer, and baking the coated polyimide-based polymerresin in an about 100° C. environment, followed by ultraviolet curing.

In example embodiments, the upper lens electrode may include an indiumzinc oxide patterned in a room temperature environment.

In example embodiments, the upper lens electrode may have a plurality ofannular patterns, and wherein each of the micro liquid crystal lenses issurrounded by an annular pattern of the plurality of annular patterns.

In example embodiments, the upper lens electrode may include a pluralityof circular or elliptical openings corresponding to the micro liquidcrystal lenses.

In example embodiments, forming a lower alignment layer may includedepositing a lower lens electrode including an indium zinc oxide on theencapsulation layer in a room temperature environment, directly coatinga polyimide-based polymer resin on an exposed portion of theencapsulation layer and the lower lens electrode, and baking the coatedpolyimide-based polymer resin in an about 100° C. environment, followedby ultraviolet curing.

Therefore, the light field display device according to exampleembodiments may have the liquid crystal lens structure including themicrolens array directly integrated on the organic light emittingdisplay panel, so that an additional substrate, an adhesive, and a lowerelectrode of the liquid crystal lens required for manufacturing a liquidcrystal lens panel can be removed. Accordingly, the manufacturing costof the light field display device may be reduced, and a thickness of thelight field display device may be reduced. In addition, a flexible lightfield display device can be implemented by using a flexible organiclight emitting display panel. Users can view a natural stereoscopicimage of the multi-viewpoints. Further, the second electrode of theorganic light emitting display panel may be used as one of the drivingelectrode for controlling the liquid crystal layer and only the voltageapplied to the lens electrode may be controlled to display the 2D imageor the stereoscopic image.

In addition, the method of manufacturing the light filed display devicemay form the lower alignment layer or the lower lens electrode in therelatively low temperature environment compared with the typical liquidcrystal lens panel process, such that the liquid crystal lens structureincluding the microlens array may be directly integrated on the organiclight emitting display panel. Accordingly, an additional substrate, anadhesive, and a lower electrode of the liquid crystal lens required formanufacturing the liquid crystal lens structure may be removed. Thus,the manufacturing cost of the light field display device may be reduced,and a thickness of the light field display device may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments can be understood in more detail from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is an exploded perspective view schematically illustrating alight field display device according to example embodiments.

FIG. 1B is schematic view illustrating an example of a user viewing astereoscopic image using the light field display device of FIG. 1A.

FIG. 2 is a cross-sectional view of a light field display deviceaccording to example embodiments.

FIG. 3A is a plan view illustrating an example of a microlens array anda lens electrode included in the light field display device of FIG. 2.

FIG. 3B is a cross-sectional view schematically illustrating an exampleof a portion taken along a line I-I′ of FIG. 3A.

FIG. 4 is a plan view illustrating another example of a microlens arrayand a lens electrode included in the light field display device of FIG.2.

FIG. 5 is a plan view illustrating still another example of a microlensarray and a lens electrode included in the light field display device ofFIG. 2.

FIGS. 6A, 6B, and 6C are diagrams illustrating examples of relations ofarrangement between a microlens array and sub pixels of the light fielddisplay device of FIG. 2.

FIG. 7 is a cross-sectional view illustrating an example of an organiclight emitting display panel included in the light field display deviceof FIG. 2.

FIGS. 8A, 8B, 8C, 8D, and 8E are cross-sectional views for explaining amethod of manufacturing a light field display device according toexample embodiments.

FIG. 9 is a cross-sectional view of a light field display deviceaccording to example embodiments.

FIG. 10 is a cross-sectional view of a light field display deviceaccording to example embodiments.

FIG. 11 is a cross-sectional view of an example of a microlens arrayincluded in the light field display device of FIG. 10.

FIG. 12A is a plan view schematically illustrating an example of amicrolens array, an upper lens electrode, and a lower lens electrode inthe light field display device of FIG. 10.

FIG. 12B is a cross-sectional view schematically illustrating an exampleof a portion taken along a line II-II′ of FIG. 12A.

DETAILED DESCRIPTION OF EMBODIMENTS

Exemplary embodiments will be described more fully hereinafter withreference to the accompanying drawings, in which various embodiments areshown.

FIG. 1A is an exploded perspective view schematically illustrating alight field display device according to example embodiments. FIG. 1B isa schematic view illustrating an example of a user viewing astereoscopic image using the light field display device of FIG. 1A.

The light field display device 1000 may include an organic lightemitting display panel 100 having a plurality of organic light emittingdiodes and a microlens array 200 having a plurality of micro liquidcrystal lenses ML. The microlens array 200 may be integrated on theorganic light emitting display panel 100.

The organic light emitting display panel 100 may include a plurality ofpixels each having organic light emitting diodes. Each of the pixels mayinclude a plurality of sub pixels SP, e.g., a red sub pixel, a green subpixel, and a blue sub pixel. The sub pixels SP may be arranged in amatrix form in a first direction D1 and a second direction D2substantially perpendicular to the first direction D1. Each of the subpixels SP may include a pixel circuit (a back plane structure), a firstelectrode, an organic light emitting layer, and a second electrode.

The microlens array 200 may be integrated on the organic light emittingdisplay panel 100. In some embodiments, the microlens array 200 may beintegrated on an encapsulation layer (e.g., a thin film encapsulationlayer). The microlens array 200 may include a plurality of microlensesML. Lights generated on the sub pixels SP of the organic light emittingdisplay panel 100 may be passed through the microlenses ML so as togenerate a light field. Arrangements of the sub pixels SP, arrangementsof the microlenses ML, and relative positional relationships between thesub pixels SP and the microlenses ML may be implemented in variousembodiments to generate the light field.

The microlens array 200 may be composed of active lenses. The microlensarray 200 may generate an electric field by a voltage applied toelectrodes constituting the microlens array 200, thereby modifying anarrangement of liquid crystal molecules. In a two-dimensional (2D) imagedisplay mode, the microlens array 200 may allow an image displayed onthe organic light emitting display panel 100 to be transmitted as it is.In a stereoscopic image display mode, the microlens array 200 mayseparate a field of vision of the image of the organic light emittingdisplay panel 100. For example, in the stereoscopic image display mode,the microlens array 200 may allow multiple viewpoint images displayed onthe organic light emitting display panel 100 to form an image in acorresponding view area for each of the multiple viewpoint images usingdiffraction and refraction of light.

As illustrated in FIG. 1B, ‘Light Field’ is a concept that expresses astate in which light is distributed in space through a distribution ofrays. Using this concept, light reflected or generated from an objectmay be defined as going straight into the human eye through space, andthe three-dimensional space may comprise a multitudinous of lightfields. An individual light field may be mathematically represented by afive-dimensional Plenoptic function, for example. Accordingly, the lightfield may be represented in terms of three-dimensional spatialcoordinates (x, y, z) of a point where a ray passes through a specificplane in space and luminance with respect to a spatial direction angle(θ, ϕ) to which the ray is directed. The light field may be captured byinforming the Plenoptic function value of the light passing through thespecific plane described above. That is, the light field may be obtainedby a luminance value by (θ, ϕ) for each coordinates (x, y, z) of acertain region. For example, a 2D camera records the luminance by (θ, ϕ)with respect to a specific point (=specific viewpoint) in space. Incontrast, a light field camera for acquiring the light field may recordthe luminance by (θ, ϕ) for all the coordinate values within a certainarea.

The light field obtained by the light field camera may be displayed bythe light field display device 1000 and users 2 can view thestereoscopic image with respect to objects OJ1 and OJ2. Since the lightfield display device 1000 may realize the light field, differentstereoscopic images may be viewed as the user 2 moves. Therefore, arealistic stereoscopic image may be viewed by the light field displaydevice 1000 as compared with the existing stereoscopic image displaydevice of a stereo type or a multi-view type.

FIG. 2 is a cross-sectional view of a light field display deviceaccording to example embodiments.

Referring to FIG. 2, the light field display device 1000 may include alower substrate 110, a black plane structure, a display structure 120having a second electrode 170, an encapsulation layer 180, a loweralignment layer 220, a liquid crystal layer 230, a lens electrode 270(e.g., an upper lens electrode), and an upper substrate 290. The lightfield display device 1000 may further include an upper alignment layer250 between the liquid crystal layer 230 and the lens electrode 270. Insome embodiments, a polarizer for controlling a transmission axisdirection of light may be further disposed on the upper substrate 290.The display structure 120 may include a pixel circuit, a first electrodeon the pixel circuit, an organic light emitting layer on the firstelectrode, and the second electrode 170 on the organic light emittinglayer.

The light field display device 1000 may be divided into an organic lightemitting display panel 100 and a microlens array 200 integrated on anemitting surface of the organic light emitting display panel 100.

The microlens array 200 may include the lower alignment layer 220, theliquid crystal layer 230, the upper alignment layer 250, the lenselectrode 270, and the upper substrate 290.

The light field display device 1000 may operate in a two-dimensional(2D) image display mode for displaying a 2D image and a stereoscopicimage display mode for displaying a stereoscopic image. A directiondistribution of the liquid crystal molecules in the microlens array 200may be controlled to display the 2D image or stereoscopic image. Thedirection distribution of the liquid crystal molecules may be controlledby a voltage applied to driving electrodes disposed above and below theliquid crystal layer.

In the stereoscopic image display mode, the lens electrode 270 mayfunction as an upper driving electrode of the liquid crystal layer 230and the second electrode 170 (e.g., a cathode electrode of an organiclight emitting diode) of the organic light emitting display panel 100may function as a lower driving electrode to drive the liquid crystallayer 230. Thus, alignment directions of the liquid crystal moleculesincluded in the liquid crystal layer 230 may be appropriately adjustedby an electric field formed between the lens electrode 270 and thesecond electrode 170.

A driving voltage, e.g., ELVSS may be applied to the second electrode170 to emit light regardless of the display mode.

In the 2D image display mode, the voltage may be not applied to the lenselectrode 270 so that the electric field may be not generated in theliquid crystal layer 230 (i.e., between the second electrode 170 and thelens electrode 270). Thus, the image output from sub pixels R, G, and Bmay penetrate the liquid crystal layer 230 as it is.

The lower substrate 110 may serve as a back-plane substrate or a basedsubstrate of the light field display device 1000. The lower substrate110 may be a polymer substrate. The lower substrate may be provided as atransparent insulation substrate. For example, the lower substrate 110may include polymer materials having transparency and flexibility.

The pixel circuit, the first electrode electrically connected to thepixel circuit, the organic light emitting layer on the first electrode,the second electrode 170 facing the first electrode and covering theorganic light emitting layer may all be disposed on the lower substrate110 in order. In some embodiments, the first electrode may be providedas anode electrodes of the sub pixels R, G, and B, and the secondelectrode 170 may be provided as cathode electrodes of the sub pixels R,G, and B.

The second electrode 170 may be provided as a common electrode for theplurality of sub pixels R, G, and B. The second electrode 170 mayinclude a metal having a low work function such as aluminum Al, silverAg, tungsten (W), copper (Cu), nickel (Ni), chrome (Cr), molybdenum(Mo), titanium (Ti), platinum (Pt), tantalum (Ta), neodymium (Nd),scandium (Sc), or an alloy of the metals.

The encapsulation layer 180 (thin film encapsulation layer) forprotecting the display structure 120 may be disposed on the secondelectrode 170. The encapsulation layer 180 may be a thin filmencapsulation layer. The encapsulation layer 180 may include inorganicmaterials such as silicon nitride, and/or metal oxide, etc. In someembodiments, the encapsulation layer 180 may have a form comprising aplurality of layers in which an organic layer (or organic layers) isdisposed between inorganic layers for planarization. Accordingly, anupper surface of the encapsulation layer 180 may flat. However, theencapsulation layer 180 is not limited thereto, and the encapsulationlayer 180 may be replaced by a rigid glass substrate.

The lower alignment layer 220 may be directly disposed on theencapsulation layer 180. In some embodiments, the lower alignment layer220 may include a polyimide-based polymer resin. The lower alignmentlayer 220 may determine an initial orientation of the liquid crystalmolecules included in the liquid crystal layer 230 and determinealignment directions of the liquid crystal molecules in advance.

The lower alignment layer 220 may be directly formed on encapsulationlayer 180 by a low-temperature firing process. The lower alignment layer220 may be formed in about 100° C. environment to prevent deformation ofthe back-plane structure and the display structure 120. Thus, anoptically clear adhesive and/or an optical bonding process are notrequired.

In some embodiments, the viscosity of the polyimide-based polymer resinmay be about 1.7 cP (centi-poise) to about 3 cP. In some embodiments,the coated polyimide-based polymer resin on the encapsulation layer 180may be dried for about 1 minute in about 100° C. environment and thenmay be cured by ultraviolet rays having a wavelength about 300 nm toabout 320 nm (preferably 313 nm) and an energy of about 20 mW/cm2, suchthat the lower alignment layer 220 may be formed. Since the loweralignment layer 220 may be directly formed on the encapsulation layer180 of the organic light emitting display panel 100 in a relatively lowtemperature environment, the display structure 120 may be not deformedby the lower alignment layer 220 forming process.

The liquid crystal layer 230 including a plurality of micro liquidcrystal lenses ML for constituting the microlens array may be disposedon the lower alignment layer 220. In some embodiments, a planar shape ofeach of the micro liquid crystal lenses may have at least one ofcircular shape, elliptical shape, and hexagonal shape. The number ofviewpoints for covering output light from the sub pixels R, G, and B maybe determined based on pitches of each of the micro liquid crystallenses (e.g., a horizontal pitch and a vertical pitch) and a pitch ofthe sub pixels R, G, and B. For example, every micro liquid crystal lensmay cover 12 horizontal viewpoints and 7 vertical viewpoints.Accordingly, the stereoscopic image of multi-viewpoints may beimplemented. This will be described with reference to FIGS. 6A to 6C.

The number of horizontal viewpoints of the micro liquid crystal lens MLmay be the number of sub pixels R, G, and B in a horizontal direction(e.g., direction D1 of FIG. 1) corresponding to the horizontal pitch ofthe micro liquid crystal lens ML. The number of vertical viewpoints ofthe micro liquid crystal lens ML may be the number of sub pixels R, G,and B in a vertical direction (e.g., direction D2 of FIG. 1)substantially perpendicular to the horizontal direction corresponding tothe vertical pitch of the micro liquid crystal lens ML.

The liquid crystal layer 230 may be formed by injecting or dropping theliquid crystal between the lower alignment layer 220 and the upperalignment layer 250.

In some embodiments, the micro liquid crystal lens ML may be controlledbased on a gap control lens method using a distance difference betweendriving electrodes, a voltage control lens (VCL) method using a voltagedifference between the driving electrodes, Fresnel lens method, or thelike.

The upper alignment layer 250 may be disposed between the liquid crystallayer 230 and the lens electrode 270. In some embodiments, the upperalignment layer 250 may include the polyimide-based polymer resin. Theupper alignment layer 250 may determine the initial orientation of theliquid crystal molecules included in the liquid crystal layer 230 anddetermine the alignment directions of the liquid crystal molecules inadvance.

The lens electrode 270 may be disposed on the liquid crystal layer 230and the upper alignment layer 250. The lens electrode 270 may generatethe electric field with the second electrode 170 in the stereoscopicimage display mode. The lens electrode 270 may have annular patternssurrounding each of the micro liquid crystal lenses ML. The lenselectrode 270 may have a plurality of openings corresponding to themicro liquid crystal lenses ML. In some embodiments, an outer shape of aplanar shape of each of the annular patterns of the lens electrode 270may be substantially hexagonal. In some embodiments, the outer shape ofthe planar shape of each of the annular patterns may be substantiallytetragonal. In some embodiments, the outer shape of the planar shape ofeach of the annular patterns may be substantially circular. Since theseare examples, shapes of the annular patterns are not limited thereto.

The lens electrode 270 may include indium zinc oxide (IZO), indium tinoxide (ITO), and the like.

In some embodiments, a width W of each of the annular patterns may bewithin a range of about 3% to about 20% of a pitch of each of the microliquid crystal lenses, and the width W of each of the annular patternsmay simultaneously include different percentages within this range, i.e.the width W may vary within a single annular pattern, for example asillustrated in FIG. 3A. Accordingly, unexpected refraction anddiffraction of the light due to the arrangement of the lens electrode270 can be prevented.

The upper substrate 290 may be disposed on the lens electrode 270.

In some embodiments, the light field display device 1000 may furtherinclude a touch sensing unit on the upper substrate 290.

As described above, the light field display device 1000 according toexample embodiments may have the liquid crystal lens structure includingthe microlens array 200 directly integrated on the organic lightemitting display panel 100, so that an additional substrate and a lowerelectrode of the liquid crystal lens required for manufacturing a liquidcrystal lens panel can be removed. Accordingly, the manufacturing costof the light field display device 1000 may be reduced, and a thicknessof the light field display device 1000 may be reduced. In addition, aflexible light field display device using a flexible organic lightemitting display panel can be implemented. Users can view a naturalstereoscopic image of the multi-viewpoints. Further, the secondelectrode 170 of the organic light emitting display panel 100 may beused as one of the driving electrode for controlling the liquid crystallayer 230 and only the voltage applied to the lens electrode 270 may becontrolled to display the 2D image or the stereoscopic image.

FIG. 3A is a plan view illustrating an example of a microlens array anda lens electrode included in the light field display device of FIG. 2.FIG. 3B is a cross-sectional view schematically illustrating an exampleof a portion taken along a line I-I′ of FIG. 3A.

Referring to FIGS. 2 to 3B, the microlens array MLA may include aplurality of micro liquid crystal lenses ML.

In some embodiments, a planar shape of the micro liquid crystal lens MLmay be circular or elliptical. The micro liquid crystal lenses may bearranged apart from each other by patterns (e.g. annular patterns) ofthe lens electrode 270A (e.g., an upper lens electrode of the microlensarray). However, this is an example, and the arrangement of the microliquid crystal lenses is not limited thereto. In the circular orelliptical shape of the micro liquid crystal lenses, a portion of anyone of two adjacent micro liquid crystal lenses may be recessed so as tomaximize a fill factor of the micro liquid crystal lens ML. For example,some of edges of the circular or elliptical shape of the micro liquidcrystal lens ML may be recessed. The fill factor may be a ratio ofactual area of the micro liquid crystal lenses in a plane on which themicro liquid crystal lenses are formed.

The lens electrode 270A may include a plurality of openingscorresponding to the micro liquid lenses ML. The openings may becircular or elliptical openings. In some embodiments, the lens electrode270A may have annular patterns EP surrounding each of the micro liquidcrystal lenses. Each of the openings may be defined as the annularpattern EP. For convenience of explanation, the lens electrode 270A willbe described as a set of a plurality of annular patterns EP. That is, asillustrated in FIGS. 3A to 6C, the annual patterns EP may be dividedinto a solid line (virtual solid line). For example, the solid line maybe a border line between adjacent annular patterns EP. For example, eachannular pattern EP may be a hexagonal annular shape. For example, asillustrated in FIG. 3A, an inner shape (e.g., an inner border line) of aplanar shape of each of the annular patterns EP may be circular orelliptical shape corresponding to the micro liquid crystal lens ML andan outer shape (e.g., an outer border line) of the planar shape of eachof the annular patterns EP may be substantially hexagonal. In otherwords, the lens electrode 270A may include a plurality of circular orelliptical openings corresponding to the micro liquid lenses ML. Theannular patterns EP of the lens electrode 270 may be formed in a singleprocess.

The light generated from a sub pixel corresponding to a portion wherethe micro liquid crystal lens ML is not formed may interfere with ageneration of desired light fields for displaying stereoscopic image(e.g., crosstalk is generated). Thus, it is preferable that the portionwhere the micro liquid crystal lens ML is not formed is minimized. Insome embodiments, a width W of the annular pattern EP may be within arange of about 3% to about 20% of a pitch P of the micro liquid crystallens ML. For example, when the pitch P of the micro liquid crystal lensML is about 500 um, the width W of the annular patterns EP may be withinabout 2 micrometers (um) to about 10 um. When the pitch P of the microliquid crystal lens ML is about 55 um, the width W of the annularpatterns EP may be within about 1 um to about 5 um. Here, the pitch P ofthe micro liquid crystal lens ML may be a distance between centers ofthe neighboring micro liquid crystal lenses.

In some embodiments, the pitches of the micro liquid crystal lensesincluded in the microlens array MLA may be substantially the same eachother.

As illustrated in FIG. 3B, an encapsulation layer 180 may be disposed ona second electrode 170 of an organic light emitting display device(e.g., a cathode electrode) and a lower alignment layer 210 may bedisposed on the encapsulation layer 180. Further, a liquid crystal layer230 including the micro lenses may be disposed between an uppersubstrate 290 at which the lens electrode 270A and an upper alignmentlayer 250 are disposed and the lower alignment layer 210.

In a stereoscopic image display mode, liquid crystal molecules may berearranged by an electrical field between the lens electrode 270A havingthe annular patterns EP and the second electrode 170 (the cathodeelectrode of the organic light emitting display panel) and the lightfield may be generated.

FIG. 4 is a plan view illustrating another example of a microlens arrayand a lens electrode included in the light field display device of FIG.2.

The light field display device of the present example embodiments issubstantially the same as the light field display device explained withreference to FIG. 3A except for shapes of the lens electrode. Thus, thesame reference numerals will be used to refer to the same or like partsas those described in the example embodiments of FIG. 3A, and anyrepetitive explanation concerning the above elements will be omitted.

Referring to FIG. 4, the microlens array MLA may include a plurality ofmicro liquid crystal lenses ML.

In some embodiments, a planar shape of the micro liquid crystal lens MLsurrounded by the lens electrode 270B may be circular or elliptical. Themicro liquid crystal lenses may be arranged apart from each other bypatterns (e.g. annular patterns) of the lens electrode 270B.

In some embodiments, the lens electrode 270B may have annular patternsEP surrounding each of the micro liquid crystal lenses ML. The lenselectrode 270B may have a plurality of circular or elliptical openingscorresponding to the micro liquid crystal lenses ML. For example, aninner shape (e.g., an inner border line) of a planar shape of each ofthe annular patterns EP may be circular or elliptical shapecorresponding to the micro liquid crystal lens ML and an outer shape(e.g., an outer border line) of the planar shape of each of the annularpatterns EP may be substantially quadrilateral. A width W of the annularpattern EP ay be within a range of about 3% to about 20% of a pitch P ofthe micro liquid crystal lens ML.

In a stereoscopic image display mode, liquid crystal molecules may berearranged by an electrical field between the lens electrode 270B havingthe annular patterns EP and the second electrode (the cathode electrodeof the organic light emitting display panel) and the light field may begenerated.

FIG. 5 is a plan view illustrating still another example of a microlensarray and a lens electrode included in the light field display device ofFIG. 2.

The light field display device of the present example embodiments issubstantially the same as the light field display device explained withreference to FIG. 3A except for shapes of the lens electrode and themicro liquid crystal lens. Thus, the same reference numerals will beused to refer to the same or like parts as those described in theexample embodiments of FIG. 3A, and any repetitive explanationconcerning the above elements will be omitted.

Referring to FIG. 5, the microlens array MLA may include a plurality ofmicro liquid crystal lenses ML.

In some embodiments, a planar shape of the micro liquid crystal lens MLsurrounded by the lens electrode 270C may be substantially hexagonal.The micro liquid crystal lenses may be arranged apart from each other bypatterns (e.g. annular patterns) of the lens electrode 270C.

In some embodiments, the lens electrode 270C may have annular patternsEP surrounding each of the micro liquid crystal lenses. That is, thelens electrode 270C may have a plurality of hexagonal shape openingscorresponding to the micro liquid crystal lenses. For example, an innershape of a planar shape of each of the annular patterns EP may behexagonal shape corresponding to the micro liquid crystal lens ML and anouter shape of the planar shape of each of the annular patterns EP maybe also substantially hexagonal. A width W of the annular pattern EP maybe within a range of about 3% to about 20% of a pitch P of the microliquid crystal lens ML.

In a stereoscopic image display mode, liquid crystal molecules may berearranged by an electrical field between the lens electrode 270C havingthe annular patterns EP and the second electrode (the cathode electrodeof the organic light emitting display panel) and the light field may begenerated.

FIG. 6A to 6C are diagrams illustrating examples of relations ofarrangement between a microlens array and sub pixels of the light fielddisplay device of FIG. 2.

Referring to FIGS. 6A to 6C, the light field display device may includean organic light emitting display panel having a plurality of sub pixelsSP and a microlens array having a plurality of micro liquid crystallenses ML each surrounded by a pattern (or an annular pattern) EP of alens electrode.

The sub pixels SP may be arranged in a matrix form in a first directionD1 and a second direction D2 substantially perpendicular to the firstdirection D1. Although lines are shown in FIGS. 6A to 6C, a black matrixfor blocking light may be formed between adjacent sub pixels SP.

The sub pixels SP may include a red sub pixel R emitting red colorlight, a green sub pixel G emitting green color light, and a blue subpixel B emitting blue color light (i.e., RGB pixel structure). In someembodiments, the red sub pixel R, the green sub pixel G, and the bluesub pixel B may be repeatedly arranged along the first direction D1. Thered sub pixels R, the green sub pixels G, and the blue sub pixels B maybe successively arranged along the second direction D2, respectively.Thus, the sub pixels R, the green sub pixels G, and the blue sub pixelsB may be arranged in a stripe form.

The planar shape of the micro liquid crystal lens ML may be hexagonal.In some embodiments, lengths of two sides facing each other may belonger than lengths of the other four sides and the hexagonal shape maybe symmetrical. In some embodiments, the hexagonal shape may be regularhexagonal. In some embodiments, lengths of two sides facing each othermay be shorter than lengths of the other four sides and the hexagonalshape may be symmetrical, for example the hexagonal shape may havereflectional symmetry. In some embodiments, lengths of two sides facingeach other may be the same and the hexagonal shape may be asymmetrical.

Adjacent sides of each annular pattern EP of the lens electrodesurrounding the micro liquid crystal lenses ML may be arranged to becontact with each other to form a honeycomb structure.

Each micro liquid crystal lens ML may be tilted at a predetermined tiltangle θ with respect to the first and second directions D1 and D2. Insome embodiments, the tilt angle θ may be determined based on a pitch ofthe sub pixel SP in the first direction D1, a pitch of the sub pixel SPin the second direction D2, and the number of horizontal viewpoints ofthe micro liquid crystal lens ML.

The number of horizontal viewpoints of the micro liquid crystal lens MLmay be the number of sub pixels SP in the first direction correspondingto the horizontal pitch of the micro liquid crystal lens ML (e.g., apitch in the first direction D1). The number of vertical viewpoints ofthe micro liquid crystal lens ML may be the number of sub pixels SP inthe second direction corresponding to the vertical pitch of the microliquid crystal lens ML (e.g., a pitch in the second direction D2).

The horizontal pitch of the micro liquid crystal lens ML may be adistance between centers of the neighboring micro liquid crystal lensesin the first direction D1. The vertical pitch of the micro liquidcrystal lens ML may be a distance between centers of the neighboringmicro liquid crystal lenses in the second direction D2.

The number of horizontal viewpoints may be determined based on thenumber of sub pixels constituting one unit pixel. The number of verticalviewpoints may be determined based on the horizontal and verticalpitches of one sub pixel SP and the number of sub pixels constitutingone unit pixel.

Accordingly, the light field display device may output the stereoscopicimage of multi viewpoints (e.g., the number of viewpoints of 105 by thenumber of horizontal viewpoints 15 and the number of vertical viewpoints7) reflecting the horizontal and vertical viewpoints. Users may view anatural stereoscopic image in which a specific color is not emphasized.

As illustrated in FIG. 6B, the sub pixels SP may be arranged in a matrixform in a first direction D1 and a second direction D2 substantiallyperpendicular to the first direction D1. The sub pixels SP may include ared sub pixel R, a green sub pixel G, a blue sub pixel B, and a whitesub pixel W (i.e., RGBW pixel structure). The red, green, blue, andwhite sub pixels R, G, B, and W may be arranged in a tile form.

The planar shape of the micro liquid crystal lens ML may be hexagonal.In some embodiments, lengths of two sides facing each other may be thesame. Left and right sides of the hexagon may be substantially parallelto the second direction D2 and a line connecting upper and lowervertexes may be inclined at a predetermined angle a with respect to thesecond direction D2. Thus, the micro liquid crystal lens ML may have anasymmetric hexagonal shape. For example, the predetermined angle a maybe determined such that a distance between the upper vertex and thelower vertex of one micro liquid crystal lens ML in the first directionD1 is less than or equal to the horizontal pitch (a pitch in the firstdirection D1) of one sub pixel SP. For example, the number of horizontalviewpoints of the micro liquid crystal lens ML may be 15 and the numberof vertical viewpoints of the micro liquid crystal lens ML may be 7.

As illustrated in FIG. 6C, the sub pixels SP may include a red sub pixelR, a green sub pixel G, and a blue sub pixel B. In an N-th pixel row,the red sub pixel R, the blue sub pixel B, and a black matrix BM may berepeatedly arranged along the first direction D1, where N is a positiveinteger. In an (N+1)-th pixel row, the black matrix BM and the green subpixel G may be repeatedly arranged along the first direction D1 (i.e.,RGBG pentile pixel structure).

The planar shape of the micro liquid crystal lens ML may be hexagonal.In some embodiments, lengths of two sides facing each other may be thesame. Left and right sides of the hexagon may be substantially parallelto the second direction D2 and a line connecting upper and lowervertexes may be inclined at a predetermined angle a with respect to thesecond direction D2. Thus, the micro liquid crystal lens ML may have anasymmetric hexagonal shape. For example, the predetermined angle a maybe determined such that a distance between the upper vertex and thelower vertex of one micro liquid crystal lens ML in the first directionD1 is less than or equal to the horizontal pitch (a pitch in the firstdirection D1) of one sub pixel SP.

FIG. 7 is a cross-sectional view illustrating an example of an organiclight emitting display panel included in the light field display deviceof FIG. 2.

Referring to FIG. 7, the organic light emitting display panel 100 mayinclude a lower substrate 110, a back plane structure on the lowersubstrate, and a display structure on the back plane structure.

A transparent insulation substrate may be used as the lower substrate110.

A buffer layer 121 may be disposed on the lower substrate 110. Thebuffer layer 121 may have a multi-stacked structure including a siliconoxide layer and a silicon nitride layer. Active patterns 122 and 124 maybe disposed on the barrier layer 120. A gate insulation layer 126 may bedisposed on the buffer layer 121 to cover the active patterns 122 and124. The gate insulation layer 126 may include silicon oxide or siliconnitride. Gate electrodes 132 and 134 may be disposed on the gateinsulation layer 126. An insulating interlayer 136 may be disposed onthe gate insulation layer 126 to cover the gate electrodes 132 and 134.The insulating interlayer 136 may include silicon oxide or siliconnitride, for example. A source electrode 142 and a drain electrode 144may extend through the insulating interlayer 136 and the gate insulationlayer 126 to be in contact with a first active pattern 122.

A thin film transistor (TFT) may be defined by the first active pattern122, the gate insulation layer 126, the first gate electrode 132, thesource electrode 142 and the drain electrode 144. Additionally, acapacitor may be defined by a second active pattern 124, the gateinsulation layer 126, and the second gate electrode 134.

A via-insulation layer 146 may be disposed on the insulating interlayer136 to cover the source and drain electrodes 142 and 144. Thevia-insulation layer 146 may substantially serve as a planarizationlayer.

The display structure may be stacked on the via-insulation layer 146. Insome embodiments, the display structure may include a first electrode150, an organic light emitting layer 160 and a second electrode 170sequentially stacked on the via-insulation layer 146.

The first electrode 150 may serve as a pixel electrode, and may beprovided per each sub pixel. In some embodiment, the first electrode 150may serve as an anode of the organic light emitting display panel 100. Apixel defining layer 155 may be disposed on the via-insulation layer146, and may cover a peripheral portion of the first electrode 150. Theorganic light emitting layer 160 may be disposed on the pixel defininglayer 155 and the first electrode 150. The organic light emitting layer160 may be individually patterned for each of a red sub pixel, a greensub pixel, and a blue sub pixel to generate a different color of lightin the each sub pixel.

The second electrode 170 may be disposed on the pixel defining layer 155and the organic light emitting layer 160. In some embodiments, thesecond electrode 170 may serve as a common electrode provided on aplurality of the pixels. The second electrode 170 may face the firstelectrode 150 and may serve as a cathode electrode of the organic lightemitting display panel 100.

The encapsulation layer 180 protecting the display structure may bedisposed on the second electrode 170. The encapsulation layer 180 mayinclude an inorganic material such as silicon nitride and/or a metaloxide, for example. In some embodiments, the encapsulation layer 180 mayinclude a first inorganic layer 181 including the inorganic material, anorganic layer 182 disposed on the first inorganic layer 181 for servingas a planarization layer, and a second inorganic layer 183 disposed onthe organic layer 182 for serving as an encapsulation. The organic layer182 may include an organic material such as polyimide, epoxy-basedresin, acrylic-based resin, polyester, and/or the like. In someembodiments, the inorganic material of the first inorganic layer 181 maybe different from the inorganic material of the second inorganic layer183. For example, the first inorganic layer 181 may include the siliconoxide and the second inorganic layer 183 may include the siliconnitride.

In some embodiments, the encapsulation layer 180 is not limited thereto,and the encapsulation layer 180 may be replaced by a rigid glasssubstrate.

A lower alignment layer or a lower lens electrode may be directlydisposed on the planarized encapsulation layer 180.

FIGS. 8A to 8E are cross-sectional views for explaining a method ofmanufacturing a light field display device according to exampleembodiments.

Referring to FIGS. 8A to 8E, the method of manufacturing the light fielddisplay device may include forming an organic light emitting displaypanel in which a lower substrate, a back plane structure, a firstelectrode, a organic light emitting layer, a second electrode, and anencapsulation layer covering the second electrode are sequentiallystacked, forming a lower alignment layer on the encapsulation layer,patterning an upper lens electrode on a lower surface of an uppersubstrate, the upper lens electrode forming an electric field with thesecond electrode, forming an upper alignment layer on the lower surfaceof the upper substrate to cover the upper lens electrode, forming aliquid crystal layer on the lower alignment layer or the upper alignmentlayer to constitute a microlens array having a plurality of micro liquidcrystal lenses, and attaching the upper substrate to the encapsulationlayer so that the liquid crystal layer is between the lower alignmentlayer and the upper alignment.

As illustrated in FIGS. 7 and 8A, the organic light emitting displaypanel 100 in which the lower substrate 110, the back plane structure,the first electrode, the organic light emitting layer, the secondelectrode 170, and the encapsulation layer 180 covering the secondelectrode 170 are sequentially stacked may be formed. The back planestructure, the first electrode, and the organic light emitting layer maybe included in each of a plurality of sub pixels R, G, and B. In someembodiments, the second electrode 170 may serve as a common electrodeprovided on a plurality of the sub pixels. The second electrode 170 mayface the first electrode and may serve as a cathode electrode of theorganic light emitting display panel 100. The encapsulation layer 180may include a first inorganic layer, an organic layer for planarization,and a second inorganic layer that are sequentially stacked.

A lower alignment layer 220 may be formed on the encapsulation layer180. In some embodiments, the lower alignment layer 220 may include apolyimide-based polymer resin. In some embodiments, the viscosity of thepolyimide-based polymer resin may be about 1.7 cP (centi-poise) to about3 cP. The lower alignment layer 220 may be directly formed onencapsulation layer 180 by a low-temperature firing process. In someembodiments, the polyimide-based polymer resin may be directly coated onthe encapsulation layer 180 using a spin coating process, a bar coatingprocess, or the like. Then, the coated polyimide-based polymer resin maybe baked for about 1 minute in about 100° C. environment and then may becured by ultraviolet rays having a wavelength about 300 nm to about 320nm (preferably 313 nm) and an energy of about 20 mW/cm2, such that thelower alignment layer 220 may be formed. The lower alignment layer 220may be directly formed on the encapsulation layer 180 of the organiclight emitting display panel 100 in a relatively low temperatureenvironment. Thus, deformation of the display structure caused bydirectly forming the lower alignment layer 220 on the encapsulationlayer 180 may be prevented.

In some embodiments, a lower lens electrode including an indium-zincoxide may be deposited on the encapsulation layer 180 before forming thelower alignment layer 220. Then, the polyimide-based polymer resin maybe coated on the deposited lower lens electrode and exposed portions ofthe encapsulation layer 180 and the coated polyimide-based polymer resinmay be baked in about 100° C. environment. Then, the bakedpolyimide-based polymer resin may be cured by the ultraviolet raysexposure to form the lower alignment layer 220. That is, the lower lenselectrode driving the liquid crystal layer may be formed on theencapsulation layer 180.

As illustrated in FIG. 8B, the upper lens electrode 270 may be patternedon the lower surface of the upper substrate 290. The upper lenselectrode 270 may generate the electric field with the second electrode170 in a stereoscopic image display mode. An arrangement of liquidcrystal molecules may be controlled by the electric field. The upperlens electrode 270 may have annular patterns or honeycomb patternssurrounding each of the micro liquid crystal lenses. In someembodiments, the upper lens electrode 270 may have a plurality ofopenings. A planar shape of each of the openings may be substantiallyhexagonal, circular or elliptical.

In some embodiments, a width W of each of the patterns may be within arange of about 3% to about 20% of a pitch of each of the micro liquidcrystal lenses.

The upper lens electrode 270 may include a transparent conductivematerial having a high work function. In some embodiments, the upperlens electrode 270 may be formed by patterning an indium tin oxide in aroom temperature environment (about 20° C. to about 30° C.). However,this is an example, and the upper lens electrode 270 may include indiumzinc oxide, zinc oxide or indium oxide, and the like.

Then, as illustrated in FIG. 8C, the upper alignment layer 250 coveringthe upper lens electrode 270 may be formed on the lower surface of theupper substrate 290. The upper alignment layer 250 may havesubstantially the same material as the lower alignment 220. In someembodiments, the upper alignment layer 250 may be formed bysubstantially the same process as the lower alignment layer 220. Forexample, the upper alignment layer 250 may be also formed in the lowtemperature environment of about 100° C. environment.

Then, as illustrated in FIG. 8D, the liquid crystal layer 230 may beformed on the lower alignment layer 220 to constitute a microlens arrayhaving a plurality of micro liquid crystal lenses ML. In someembodiments, sealants 235 may be formed on the lower alignment layer 220and the liquid crystal may be injected or dropped between sealants 235.

Then, as illustrated in FIG. 8E, the upper substrate 290 that the upperelectrode 270 and the upper alignment layer 250 are formed may beattached to the encapsulation layer that the lower alignment layer 220and the liquid crystal layer 230 are formed so that the liquid crystallayer 230 may be disposed between the lower alignment layer 220 and theupper alignment layer 250. For example, the sealants 235 may be cured byultraviolet lays exposure so that the upper substrate 290 and theencapsulation layer may be attached.

As described above, the method of manufacturing the light field displaydevice may form the lower alignment layer 220 in the relatively lowtemperature environment such that the liquid crystal lens structureincluding the micro lens array may be directly integrated on the organiclight emitting display panel 100. Accordingly, an additional substrateand a lower electrode of the liquid crystal lens required formanufacturing the liquid crystal lens structure may be removed. Thus,the manufacturing cost of the light field display device may be reduced,and a thickness of the light field display device may be reduced. Inaddition, a flexible light field display device using a flexible organiclight emitting display panel can be implemented.

FIG. 9 is a cross-sectional view of a light field display deviceaccording to example embodiments.

The light field display device of the present example embodiments issubstantially the same as the light field display device explained withreference to FIGS. 2 to 7 except for a construction of a lower lenselectrode and a lower alignment layer. Thus, the same reference numeralswill be used to refer to the same or like parts as those described inthe example embodiments of FIG. 2, and any repetitive explanationconcerning the above elements will be omitted.

Referring to FIG. 9, the light field display device 2000 may include anorganic light emitting display panel 100 having a lower substrate 110,an encapsulation layer 180, and a plurality of sub pixels R, G, Barranged in a matrix form between the lower substrate 110 and theencapsulation layer 180, a lower lens electrode 210, a lower alignmentlayer 220, a liquid crystal layer 230, an upper alignment layer 250, anupper lens electrode 270, and an upper substrate 290. In someembodiments, a polarizer for controlling a transmission axis directionof light may be further disposed on the upper substrate 290.

The light field display device 2000 may be divided into an organic lightemitting display panel 100 and a microlens array 200 integrated on anemitting surface of the organic light emitting display panel 100.

Since the constructions of the organic light emitting display panel 100are described above with reference to FIGS. 2 and 7, duplicateddescriptions will not be repeated.

In a stereoscopic image display mode, the upper lens electrode 270 mayfunction as an upper driving electrode of the liquid crystal layer 230.In the stereoscopic image display mode, the lower lens electrode 220and/or the second electrode 170 (e.g., a cathode electrode of an organiclight emitting diode) of the organic light emitting display panel 100may function as a lower driving electrode to drive the liquid crystallayer 230. Thus, alignment directions of the liquid crystal moleculesincluded in the liquid crystal layer 230 may be appropriately adjustedby an electric field formed between the upper lens electrode 270 and thelower lens electrode (or the second electrode 170).

The lower lens electrode 210 may be directly disposed on theencapsulation layer 180. In some embodiments, the lower lens electrode210 may include indium zinc oxide. The lower lens electrode 210 may bedirectly deposited on the encapsulation layer 180 in a room temperature(about 20° C. to about 30° C.). In some embodiments, the lower lenselectrode 210 may face the sub pixels R, G, and B. The lower lenselectrode 210 may be disposed as a common electrode.

The lower alignment layer 220 may be disposed on the lower lenselectrode 210 by a low-temperature firing process of a polyimide-basedpolymer resin. The lower alignment layer 220 may be formed in about 100°C. environment to prevent deformation of the organic light emittingdisplay panel 100.

Since the lower lens electrode 210 and the lower alignment layer 220 maybe formed in a relatively low temperature, the lower lens electrode 210and the lower alignment layer 220 can be integrated on the heatsensitive organic light emitting display panel 100.

The liquid crystal layer 230 including a plurality of micro liquidcrystal lenses for constituting the microlens array may be disposed onthe lower alignment layer 220. In some embodiments, a planar shape ofeach of the micro liquid crystal lenses may have at least one ofcircular shape, elliptical shape, and hexagonal shape. The liquidcrystal layer 230 may be formed by injecting or dropping the liquidcrystal between the lower alignment layer 220 and the upper alignmentlayer 250.

The upper alignment layer 250 may be disposed between the liquid crystallayer 230 and the upper lens electrode 270. In some embodiments, theupper alignment layer 250 may include the polyimide-based polymer resin.

The upper lens electrode 270 may be disposed on the liquid crystal layer230 and the upper alignment layer 250. The upper lens electrode 270 maygenerate the electric field with the second electrode 170 (and/or thelower lens electrode 210) in the stereoscopic image display mode. Theupper lens electrode 270 may have annular patterns surrounding each ofthe micro liquid crystal lenses. In some embodiments, an outer shape ofa planar shape of each of the annular patterns of the upper lenselectrode 270 may be substantially hexagonal. In some embodiments, theouter shape of the planar shape of each of the annular patterns may besubstantially tetragonal. In some embodiments, the outer shape of theplanar shape of each of the annular patterns may be substantiallycircular. Since these are examples, shapes of the annular patterns arenot limited thereto.

In some embodiments, a width W of each of the annular patterns may bewithin a range of about 3% to about 20% of a pitch of each of the microliquid crystal lenses. Accordingly, unexpected refraction anddiffraction of the light due to the arrangement of the upper lenselectrode 270 can be prevented.

The upper substrate 290 may be disposed on the upper lens electrode 270.

In some embodiments, the light field display device 2000 may furtherinclude a touch sensing unit on the upper substrate 290.

As described above, the light field display device 2000 according toexample embodiments may have the liquid crystal lens structure includingthe microlens array 200 directly integrated on the organic lightemitting display panel 100, so that an additional substrate required formanufacturing a liquid crystal lens panel can be removed. Accordingly,the manufacturing cost of the light field display device 2000 may bereduced, and a thickness of the light field display device 2000 may bereduced. In addition, a flexible light field display device using aflexible organic light emitting display panel can be implemented.

FIG. 10 is a cross-sectional view of a light field display deviceaccording to example embodiments.

The light field display device of the present example embodiments issubstantially the same as the light field display device explained withreference to FIGS. 2 to 7 except for constructions of a lower lenselectrode and an upper lens electrode. Thus, the same reference numeralswill be used to refer to the same or like parts as those described inthe example embodiments of FIG. 2, and any repetitive explanationconcerning the above elements will be omitted.

Referring to FIG. 10, the light field display device 3000 may include anorganic light emitting display panel 100 having a lower substrate 110,an encapsulation layer 180, and a plurality of sub pixels R, G, Barranged in a matrix form between the lower substrate 110 and theencapsulation layer 180, a lower lens electrode 212, a lower alignmentlayer 222, a liquid crystal layer 230, an upper alignment layer 252, anupper lens electrode 272, and an upper substrate 290. In someembodiments, a polarizer for controlling a transmission axis directionof light may be further disposed on the upper substrate 290. In someembodiments, a touch sensing unit for recognizing touches may be furtherdisposed on the upper substrate 290.

In a stereoscopic image display mode, the upper lens electrode 272 mayfunction as an upper driving electrode of the liquid crystal layer 230.In the stereoscopic image display mode, the lower lens electrode 212and/or the second electrode 170 (e.g., a cathode electrode of an organiclight emitting diode) of the organic light emitting display panel 100may function as a lower driving electrode to drive the liquid crystallayer 230.

The lower lens electrode 212 may be directly patterned on theencapsulation layer 180. In some embodiments, the lower lens electrode212 may include indium zinc oxide. The lower lens electrode 210 may bedirectly deposited on the encapsulation layer 180 in a room temperature(about 20° C. to about 30° C.). . In some embodiments, the lower lenselectrode 212 may have annular patterns surrounding each micro liquidcrystal lens. In some embodiments, an outer shape of a planar shape ofeach of the annular patterns of the lower lens electrode 212 may besubstantially hexagonal. In some embodiments, the outer shape of theplanar shape of each of the annular patterns may be substantiallytetragonal. In some embodiments, the outer shape of the planar shape ofeach of the annular patterns may be substantially circular. Since theseare examples, shapes of the annular patterns are not limited thereto.

The lower alignment layer 222 may be disposed on the encapsulation layer180 covering the patterned lower lens electrode 212 by a low-temperaturefiring process of a polyimide-based polymer resin. The lower alignmentlayer 222 may be formed in about 100° C. environment to preventdeformation of the organic light emitting display panel 100.

The liquid crystal layer 230 including a plurality of micro liquidcrystal lenses for constituting the microlens array may be disposed onthe lower alignment layer 222.

The upper alignment layer 252 may be disposed between the liquid crystallayer 230 and the upper lens electrode 272. In some embodiments, theupper alignment layer 252 may include the polyimide-based polymer resin.

The upper lens electrode 272 may be disposed on the upper alignmentlayer 252. The upper lens electrode 272 may generate the electric fieldwith the second electrode 170 and/or the lower lens electrode 212 in thestereoscopic image display mode. In some embodiments, the upper lenselectrode 272 may face the sub pixels R, G, and B. The upper lenselectrode 272 may be disposed as a common electrode.

Accordingly, the light field display device 3000 according to exampleembodiments may have the liquid crystal lens structure including themicrolens array 200 directly integrated on the organic light emittingdisplay panel 100, so that an additional substrate required formanufacturing a liquid crystal lens panel can be removed.

FIG. 11 is a cross-sectional view of an example of a microlens arrayincluded in the light field display device of FIG. 10.

Referring to FIG. 11, the patterned lower lens electrode 212 may bedisposed on the encapsulation layer 180 of the organic light emittingdisplay panel and the lower alignment layer 222 covering the patternedlower lens electrode 212 may be also disposed on the encapsulation layer180. The liquid crystal layer 230 having micro liquid crystal lenses maybe disposed between the lower alignment layer 252 and the uppersubstrate 290 where the upper lens electrode 272 and the upper alignmentlayer 252 are formed.

In the stereoscopic image display mode, liquid crystal molecules may berearranged by an electrical field between the lower lens electrode 212having annular patterns and the upper lens electrode 272 having thecommon electrode pattern and the light field may be generated.

FIG. 12A is a plan view schematically illustrating an example of amicrolens array, an upper lens electrode, and a lower lens electrode inthe light field display device of FIG. 10. FIG. 12B is a cross-sectionalview schematically illustrating an example of a portion taken along aline II-II′ of FIG. 12A.

Referring to FIGS. 10, 12A, and 12B, the lower lens electrode 214 andthe upper lens electrode 274 may have annular patterns EP1 and EP2 eachsurrounding different micro liquid crystal lenses.

In some embodiments, the lower lens electrode 214 and the upper lenselectrode 274 may have annular patterns EP1 and EP2 alternating witheach other in a first direction D1 in which the micro liquid crystallenses ML are arranged. For example, one of the lower and upper lenselectrodes 214 and 274 may be the annular pattern and the other may havea flat electrode portion for one micro liquid crystal lens ML.

As illustrated in FIG. 12B, the lower lens electrode 214 may have theannular pattern portion 214A (e.g., represented as EP1 in FIG. 12A)surrounding a first micro liquid crystal lens ML1 and may have the flatelectrode portion 214B corresponding to a second micro liquid crystallens ML2 adjacent to the first micro liquid crystal lens ML1 in thefirst direction D1. For example, the lower lens electrode 214 may haveholes corresponding to some of the micro lenses in the first directionD1. In addition, the upper lens electrode 274 may have the annularpattern portion 274A (e.g., represented as EP2 in FIG. 12A) surroundingthe second micro liquid crystal lens ML2 and may have the flat electrodeportion 274B corresponding to the first micro liquid crystal lens ML1.For example, the upper lens electrode 274 may have holes correspondingto some of the micro lenses in the first direction D1. Each of the holesof the upper lens electrode 274 does not overlap the holes of the lowerlens electrode 214.

In some embodiments, in the micro liquid crystal lenses which areadjacent to each other in the first direction D1 (e.g., the first andsecond micro liquid crystal lenses ML1 and ML2), a part of an edge ofthe flat electrode portion 214B of the lower lens electrode 214 mayoverlap a part of an edge of the flat electrode portion 274B of theupper lens electrode 274.

Accordingly, the upper and lower lens electrodes 274 and 214 forming themicrolens array may be patterned at different positions corresponding tothe positions of the micro liquid crystal lenses.

As described above, shapes of the micro liquid crystal lenses and thelens electrodes may be adjusted so that the multiple viewpointstereoscopic images having a high resolution of 2000 PPI (pixels perinch) or more can be implemented.

The present embodiments may be applied to any display device applyingthe light filed display. For example, the present embodiments may beapplied to a television, a computer monitor, a laptop, a digital camera,a cellular phone, a smart phone, a smart pad, a personal digitalassistant (PDA), a portable multimedia player (PMP), a MP3 player, anavigation system, a game console, a video phone, a head up displaysystem, a wearable display device, etc.

The foregoing is illustrative of example embodiments, and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the novel teachings and advantages of exampleembodiments. Accordingly, all such modifications are intended to beincluded within the scope of example embodiments as defined in theclaims. In the claims, means-plus-function clauses are intended to coverthe structures described herein as performing the recited function andnot only structural equivalents but also equivalent structures.Therefore, it is to be understood that the foregoing is illustrative ofexample embodiments and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedexample embodiments, as well as other example embodiments, are intendedto be included within the scope of the appended claims. The inventiveconcept is defined by the following claims, with equivalents of theclaims to be included therein.

What is claimed is:
 1. A light field display device, comprising: anorganic light emitting display panel including a lower substrate, anencapsulation layer, and a plurality of sub pixels arranged in a matrixform between the lower substrate and the encapsulation layer; a lowerlens electrode directly on the encapsulation layer; a lower alignmentlayer directly on the encapsulation layer; a liquid crystal layer on thelower alignment layer, the liquid crystal layer including a plurality ofmicro liquid crystal lenses to constitute a microlens array; an upperalignment layer on the liquid crystal layer; an upper lens electrode onthe liquid crystal layer to form an electric field with the lowerelectrode lens by receiving a voltage; and an upper substrate on theupper lens electrode.
 2. The device of claim 1, wherein the lower lenselectrode is facing the sub pixels in common, wherein the upper lenselectrode has a plurality of annular patterns, and wherein each of themicro liquid crystal lenses is surrounded by an annular pattern of theplurality of annular patterns.
 3. The device of claim 1, wherein theupper lens electrode is facing the sub pixels in common, wherein thelower lens electrode has a plurality of annular patterns, and whereineach of the micro liquid crystal lenses is surrounded by an annularpattern of the plurality of annular patterns.
 4. The device of claim 1,wherein the lower lens electrode and the upper lens electrode haveannular patterns alternating with each other in a first direction inwhich the micro liquid crystal lenses are arranged, and wherein a partof an edge of the lower lens electrode overlaps a part of an edge of theupper lens electrode.